Concrete calculators that give you yards, bags, weight and cost

Concrete Calculators

• Concrete CalculatorCubic yards, bags and weight for slabs, footings, columns, steps and curbs.
• Concrete Slab Cost CalculatorReady-mix versus bagged cost for a slab, including delivery and short-load fees.
• Concrete Bag CalculatorHow many 40, 50, 60 or 80 lb bags a pour needs, by published bag yield.
• Post Hole Concrete CalculatorConcrete per hole and per fence run, with the post volume subtracted.
• Rebar CalculatorBar count, total length, lap splices and weight for a slab or footing grid.

Aggregate & Volume Calculators

• Cubic Yard CalculatorConvert any length, width and depth into cubic yards, feet and tons.
• Gravel CalculatorTons and cubic yards of gravel, crushed stone or road base for any area.
• Sand CalculatorBedding, paver and fill sand quantities by volume, weight and bag count.

Masonry Calculators

• Paver CalculatorPaver count, bedding sand and base gravel for a patio, walk or driveway.
• Retaining Wall Block CalculatorBlock count by course, cap blocks, base gravel and drainage stone.

Reference Charts

• Concrete Mix Ratio ChartCement, sand and gravel proportions and water-cement ratio by target strength.
• Rebar Size ChartBar designation, diameter, cross-sectional area and weight per foot.
• Concrete Curing TimeStrength gain by day, walk-on and drive-on times, and cold-weather effects.

Concrete by slab size

Common slab sizes with the volume, bag count and cost already worked out.

• 4 x 4 ft
• 6 x 6 ft
• 8 x 8 ft
• 10 x 10 ft
• 10 x 12 ft
• 10 x 20 ft
• 12 x 12 ft
• 12 x 16 ft
• 12 x 20 ft
• 12 x 24 ft
• 16 x 16 ft
• 16 x 20 ft
• 20 x 20 ft
• 20 x 24 ft
• 24 x 24 ft
• 24 x 30 ft
• 30 x 30 ft
• 30 x 40 ft
• 40 x 60 ft

Pour-day essentials

The tools that decide whether a slab finishes flat. Sourced from Amazon.

Links below are affiliate links. If you buy through them we may earn a commission at no extra cost to you.

• Magnesium bull floatFlattens and closes the surface right after screeding.Every slab · Check price
• Screed board / power screedStrikes the slab to grade before it starts to set.Slabs · Check price
• Concrete mixer (1.5–4 cu ft)Faster and more consistent than mixing bags in a wheelbarrow.Bagged pours · Check price
• Contractor wheelbarrow6 cu ft steel tray moves roughly 300 lb of wet mix per trip.Every pour · Check price
• Edger, groover and steel trowelRadius the edges and cut control joints before the slab hardens.Finishing · Check price
• Rubber boots and nitrile glovesWet concrete is caustic — cover skin before you stand in it.Safety · Check price

Frequently asked questions

How much concrete do I need?

Multiply length by width by thickness in feet to get cubic feet, then divide by 27 for cubic yards. A 10 x 10 ft slab at 4 inches thick is 10 x 10 x 0.333 = 33.3 cubic feet, or 1.23 cubic yards. Order about 10 percent extra for subgrade variation and spillage.

How many 80 lb bags of concrete are in a cubic yard?

An 80 lb bag yields 0.60 cubic feet of mixed concrete, so a cubic yard (27 cubic feet) takes 45 bags. A 60 lb bag yields 0.45 cubic feet (60 bags per yard) and a 40 lb bag yields 0.30 cubic feet (90 bags per yard).

When is ready-mix cheaper than bags?

Bags win below roughly half a cubic yard. Above about one cubic yard ready-mix is almost always cheaper per yard and far less work, though short-load fees apply below the truck minimum, which is typically 3 to 5 yards.

Are these calculators free?

Yes. Every calculator on CementCalc runs in your browser, needs no signup, and returns cubic yards, bag counts, weight and cost in one pass.